Thank you so much... these comments help....
I am also at 5 wks now, but when I got my results back from the blood test they were a week ahead ... dont know if that helps or not, but you should be able to go for an ultra sound and another blood test n they should be able to tell you for sure
Once you get an ultrasound you'll know the dates better when we were trying to figure out the date of mine we were a week off, I wouldn't worry to much about it :)